Headgear

ABSTRACT

A personalised cap ( 10 ) for use with a protective helmet is disclosed, having crown and brow portions ( 12, 14 ). The brow portion ( 14 ) is removable independently of the crown portion ( 10 ), and an alternative brow portion ( 14 ′) is provided for use when a environmental protection hood is to be worn under the helmet. An alternative crown portion ( 12 ′) also may be provided. A hood for use over a helmet and a hose for use to provide air to a respiratory mask, a mask and fittings for attaching a mask to a helmet are also disclosed. The environmental protection hood may comprise a manifold ( 412 ) having an element external to the hood, for receiving supply of services needed within the hood, and an element internal to the hood, for providing those services where required.

The present invention relates to headgear. In one alternative, theinvention relates in particular, but not exclusively, to a personalisedinternal cap for a helmet, a helmet comprising a personalised internalcap, a method of manufacturing such a helmet and protective apparelcomprising such a helmet, wherein the internal cap is personalised suchthat the helmet sits in a predetermined position on a wearer's head. Ina second alternative, the invention relates, in particular, but notexclusively, to an environmental protection hood. In a thirdalternative, the invention relates to breathing equipment and inparticular, but not exclusively, to breathing masks, such as those wornby the pilots of military aircraft.

The invention is particularly suitable for the fitting of helmets forpilots of military aircraft. Such helmets typically comprise an outerprotective helmet and, attached to the outer helmet, a helmet mounteddisplay system. Such systems require exact and repeatable placement ofimages in front of the wearer's eyes during flight. A poorly-fittinghelmet tends to move relative to the head during use, thus causing thedisplay to be displaced relative to the line of sight of the wearer.This is particularly important if the display is for a weapon-aimingsystem. A poorly-fitting helmet also causes the weight of the helmet tobe focussed on pressure points, resulting in user discomfort.

In some situations it is necessary for the wearer to wear anenvironmental protection hood, within or outside the helmet. Such hoodstypically have a plurality of tubes extending through the hood atvarious locations to supply services such as air, oxygen liquid andcommunications to the wearer. Each of these penetrations of the hood isa potential leakage path and hazard. Additionally, the presence of thehood may result in the helmet not sitting in the necessary position foracceptable operation of the external helmet-mounted equipment. Inaddition, the hood may cause discomfort to the wearer. Tailoring hoodsto prevent this may not be cost-effective. In addition, the materialfrom which the hood is made may not be conducive to an accurate andrepeatable fit of the helmet to the head of the wearer, for examplesince it slips against the hair of the wearer.

Additionally, the pilot of a military aircraft typically wears abreathing mask which is attached by straps for, example, to a helmet.The mask has to be located within the hood so that a problem arises whenconnecting the mask to the helmet, in the event that the hood is wornunder the helmet. If openings are provided in the hood to receive strapsconnecting the mask to the helmet, the openings will need to be sealedto ensure the integrity of the hood. If the seals become damaged ordistorted in use, the health of the pilot may be placed at risk. Similarproblems may arise in the case of breathing masks provided for use ofthose working in toxic atmospheres.

An aspect of this invention, whose aim is to overcome or alleviate oneor more of these problems, provides an environmental protection hoodcomprising a manifold having an element external to the hood, forreceiving supply of services needed within the hood, and an elementinternal to the hood, for providing those services where required.

Provision of all the services at a specialised manifold assists inenabling a variety of different hoods, masks and helmets to be usedtogether. Furthermore, it assists in stabilising the hood in use. Anexoskeleton may be provided with the manifold, as described hereinafter,which greatly assists the stabilisation. Additionally, the provision ofa manifold in this way may eliminate the necessity for a plurality ofopenings in the hood and thereby reduce the likelihood of failure due toleakage around such an opening. Additional inlets and outlets may beadded to the hood much more easily, being sealed to the manifold.

The external element may have an inlet for receiving a breathing supplyand/or the internal element may have an outlet for feeding an oxygenmask.

The external element may have an inlet for receiving a liquid.

The external element may have an inlet for receiving air and theinternal element may have an outlet for feeding a demisting jet of airfor demisting or inhibiting misting of a window of the hood and/or anoutlet for ventilating the hood.

Preferably the inlet for receiving air is disposed within the inlet forreceiving a breathing supply or vice versa.

A supply conduit assembly for connection to a hood according to thefirst aspect of the invention may be provided comprising a breathing gasconduit, an air conduit and a diverter for diverting air from the airconduit to the breathing conduit if a supply of breathing gas isinsufficient.

The assembly may comprise a powered impeller for increasing air pressurein the air conduit.

The air conduit may comprise a filter for removing contaminants from theair passing therethrough.

The diverter may comprise a normally-closed valve between the breathinggas conduit and the air conduit.

The assembly may comprise a non-return valve to prevent air flowing backfrom the hood when air is diverted to the breathing conduit.

A manifold for a hood according to the first aspect of the invention orfor an assembly as set out above may also be provided.

A further aspect of the invention, whose aim is to overcome or alleviateone or more of the above problems, provides a personalised cap for ahelmet, the cap being bespoke to a specific wearer so as precisely tofit the helmet to the wearer's head, the cap comprising a crown portionand a separate brow portion, the crown and brow portion being contiguouswith each other.

The provision of a tailored cap in this way allows the general use ofhoods and helmets provided in a limited number of sizes. In addition,the hood may be formed of a material best-suited to the protectivepurpose which the hood is intended to perform, while the cap is formedof a material which will not slide against the hair of the wearer.

A further aspect of the invention provides an environmental protectionhood for use under a protective helmet, comprising an aperturecontaining a window adjacent the periphery of which is adapted to engagewith a personalised cap according to the second aspect of the invention.

Such a hood may serve to locate accurately the window relative to thehead of a wearer.

Yet a further aspect provides a helmet comprising a personalised cap asset out above.

A further aspect provides a method of manufacturing a helmet comprisinga personalised internal cap which positions the helmet on the wearer'shead, the method comprising a prior determination of the shape of thewearer's head by a measurement device followed by the production of akit of parts for assembly into said personalised cap, the kit comprisinga crown portion and alternative brow portions, a first said brow portionconforming to the wearer's head when wearing an environmental protectionhood, and a second said brow portion conforming to the wearer's headwithout said hood. There may also be provided alternative crownportions, a first said crown portion conforming to the wearer's headwhen wearing an environmental protection hood, and a second said crownportion conforming to the wearer's head without said hood.

Yet a further aspect provides a kit of parts for precisely fitting ahelmet to a wearer's head, the kit comprising a crown portion and firstand second brow portions of a personalised internal cap which positionthe helmet on the wearer's head, the first and second brow portionshaving respectively been produced to align the helmet on the wearer'shead to a predetermined position relative to his eyes when the wearerrespectively is wearing and is not wearing an environmental protectionhood. The kit may also comprise a second crown portion, the first andsecond crown portions having respectively been produced to align thehelmet on the wearer's head to a predetermined position relative to hiseyes when the wearer respectively is wearing and is not wearing anenvironmental protection hood.

The individual components of the kit of parts may also be providedseparately, or in any combination. Thus the invention also provides acrown portion of a personalised cap for a helmet, the crown portionconforming to the shape of a wearer's head. The invention also provides,independently, first and second brow portions of a personalised cap fora helmet, the brow portions conforming to the shape of a particularwearer's head when not wearing and when wearing an environmentalprotection hood, respectively.

A related aspect of the invention provides a helmet comprising apersonalised internal cap formed from a kit of parts as set out above,and a further aspect provides protective apparel comprising such ahelmet or a helmet as set out above.

Yet a further aspect of the invention provides an environmentalprotection hood for use under a protective helmet, comprising anaperture containing a window adjacent the periphery of which is adaptedto engage with a personalised cap according to one of the above aspectsof the invention.

A further aspect of the invention provides an air supply system forsupplying air to an oxygen mask, comprising a junction having a pressureswitch adapted to supply air to a mask from a pressurised source whensuch is present and, in the absence of a pressurised source, from asecondary source adapted to be positively buoyant in water.

Yet a further aspect provides a device for supplying air to an oxygenmask, comprising an air inlet, an outlet for carrying air towards themask, the device being adapted to become positively buoyant in waterupon contact with water.

A further aspect provides a buoyancy aid or life vest comprising adevice according to the preceding aspect.

A hood according to any of the aspects set out above may furthercomprise fittings for engaging with a respiratory mask to locate such amask when used by a wearer of the hood. The provision of fittings on thehood for attaching a mask rather than attaching the mask to the helmetmay divorce the location of the mask from that of the helmet, in a hoodformed of a flexible material. This enables variations in the faciallengths of different users to be better accommodated. This may provideincreased comfort for the wearer, particularly when under exertion.

Preferably, such a hood further comprises a removable mask portion. Theprovision of a removable mask portion of the hood, for example, aroundthe mouth (and preferably nose) of the wearer, such that when theportion is removed the mouth (and nose) are exposed, may increase thecomfort of the wearer of the hood in an analogous way as the provisionof a removable window.

Preferably, the mask portion comprises a further rigid frame adapted toseal against the rigid frame. This may allow the removable mask portionto be reattached to the main body of the hood rapidly and securely.

The fittings for attaching a mask are preferably provided on the rigidframe of the mask portion, since this may allow the mask portion andmask to be attached and removed in one operation.

Yet a further aspect of the invention provides an environmentalprotection hood for use over a helmet and a respiratory mask, the hoodbeing adapted to entirely enclose the helmet and mask.

Such a hood may eliminate the need for decontamination of a helmet andmask or for the discarding of the helmet and mask, which may benecessary when using hoods in which the helmet and mask are exposed. Inaddition, masks used with such a hood need themselves be protective, anda wearer may use a single mask regardless of whether a hood is to beworn.

The hood may comprise an aperture having situated therein a windowthrough which a wearer of the hood may see, a selectively releasableseal being provided adjacent an edge of the window such that an openingmay be made in the hood. In this way, the wearer of the hood may easilycreate an opening in the hood in conditions where the wearing of thehood is not necessary (but may be anticipated), thereby increasing hiscomfort. This feature is also provided independently.

The hood may preferably be worn with a helmet having a front portionwhich may be raised and lowered by the wearer and it thereforepreferably comprises means for engaging the window with a raisable frontportion of a helmet, such that when the hood and helmet are worntogether, the window and the front portion of the helmet may be raisedand lowered together. This may further serve to increase the comfort ofthe wearer.

Preferably, the hood further comprises fittings for engaging with arespiratory mask to locate such a mask when used by a wearer of thehood.

Hoods in accordance with the preceding aspects of the invention (whetherfor use over or under a helmet) preferably further comprise a sleeveadapted to receive a hose for delivering air to a respiratory mask wornby a wearer of the hood. In this way, it is not necessary that the hoseitself is protective since it is enclosed by the sleeve. A single hosemay therefore be used regardless of whether a hood is to be worn. Thisfeature is also provided independently.

The sleeve is preferably formed of the same material as the hood so thatit too forms part of the enclosure of the hood, which thereby alsoprotects the hose.

Preferably, the distal end of the sleeve with respect to the aperture ofthe hood has an element inside the sleeve for engaging with a hose bymeans of which the hose may be fed with air and an element outside thesleeve for engaging with an air supply means of an aircraft, by means ofwhich the hose may be fed with air.

The sleeve preferably further comprises at its distal end an element forattaching a further hose for providing demisting air to the hoodadjacent the head of a wearer and has a further hose for providing thatdemisting air which runs within the sleeve from its distal end to aportion of the hood adapted in use to be adjacent the head of a wearer,where it may be directed, for example, onto the inside of the window ofthe hood.

A further aspect of the invention provides a respiratory mask air supplyhose comprising an enclosure forming a conduit through which air maypass and a structural element for maintaining the cross-section of theconduit.

The structural element is preferably formed of a thermoplastic material.

Preferably, the structural element comprises a left-handed helix and aright handed helix, both helices being coaxial with the conduit. Incomparison with known hoses air conduits which have a structural elementformed of a single helix, such a structural means may have greaterstructural stability. This feature is also provided separately.

Preferably, the helices are arranged such that, when the hose iscompressed or extended, substantially zero torque around the axis of thehose results In this way, if the user of the hose moves towards or awayfrom an air source to which the hose is attached, the likelihood ofaccidental detachment of the hose by rotation of the attached end undera resultant torque and the risk of a kink forming in the hose may bereduced.

Preferably, the structural element comprises a plurality of left-handedhelices and/or a plurality of right-handed helices. This may allowmechanical characteristics of the hose (e.g. stiffness) to be tailoredto particular applications.

The structural element may comprise a mesh. The structural element maybe extruded.

The structural element may be formed of different material from that ofthe enclosure. In comparison with known hoses which are formed entirelyof moulded silicone and which have integral ribs to maintain thestructure of the hose, such a hose may be made to be lighter byselection of an appropriate material for the structural means, which mayin turn result in greatly reduced load on the head of a wearer,particularly under rapid acceleration.

A further aspect provides a respirator mask comprising a first portion(which is preferably injection moulded) housing at least one valve and asecond portion (for example, formed of silicone rubber) adapted to sealaround the nose and mouth of a wearer, the first and second portionsbeing formed of different materials.

Known respirator masks are largely formed of a flexible material such assilicone rubber in order to provide sufficient flexibility for the maskto seal around the nose and mouth of a wearer. The rigidity necessaryfor the portion of the mask housing the inspiratory and expiratoryvalves and the communications components is achieved by means of largerwall sections. In comparison with such known masks, a mask according tothis aspect may be lighter since the necessary rigidity may be achievedby thinner wall sections of a less dense material (e.g. a thermoplasticsmaterial such as nylon, PA or POM). In addition, the centre of gravityof the mask may be moved towards the seal of the mask. Both the reducedweight and the movement of the centre of gravity are of particularimportance where the wearer of the mask is to be subjected to increasedaccelerational forces, where they may result in a reduced load on theneck of the wearer. This may result in the mask being usable inconditions where the wearer is subjected to yet greater accelerationalforces. Furthermore, the tension necessary to securely locate the maskin place may be reduced, resulting in greater comfort for the wearer.

Preferably, the first portion of the mask has at least oneintegrally-formed portion of a valve. This feature is also providedindependently. In known masks, the valves are self-contained units made,tested and sold separately and inserted into the mask. The mask istherefore relatively large since it accommodates both the wall thicknessnecessary to give the structural portion of the mask rigidity and thewall thickness of the valves. The provision of a portion of the valve(for example, a valve seat or a chamber of an inspiratory or expiratoryvalve) integrally with the portion of the mask may reduce the overallwall thickness of the mask, perhaps resulting in a yet lighter, morecompact mask having the advantages set out above. In addition, thereduced number of interfaces between components of the mask may reducethe likelihood of leaks forming around valves.

A further aspect of the invention provides a fitting for attaching arespirator mask to a helmet, the fitting comprising a helmet connectorfor engaging with a helmet, and a mask connector for receiving webbingfor attaching the fitting to the mask, the mask connector being adaptedto be movable such that the direction at which webbing in the maskconnector extends from the fitting relative to the position of thehelmet engaging means may be adjusted. In this way, the attitude of amask attached to the fitting may be adjusted independently of theattitude of the fitting relative to the helmet, which may result inincreased comfort for a wearer.

Preferably, the fitting comprises a plurality of independently-moveablemask connectors. This may result in greater security in the attitude ofthe mask relative to the fitting.

The mask connector preferably comprises a disc rotatably-mounted in thefitting, the disk comprising a slot for receiving webbing and/or anarcuate insert slidably mounted in an arcuate slot in the fitting, theinsert comprising a further slot for receiving webbing.

According to a further aspect of the present invention a breathing maskhas a component for location within the hood and a component forlocation externally of the hood. Preferably the external component maybe attached to the helmet, and preferably the external component isadapted to capture the material of the hood between the internalcomponent and the external component.

Preferably one of the components being provided or associated with aprojection capable of being pressed into the material of the hood, andthe other component having an opening for receiving and retaining theprojection and the portion of the hood to which it is applied.

Preferably the projection has an enlarged head which, together with theportion of the hood, is retained in the opening eg. as a snap-fit. Theprojection may be of mushroom-like form and be provided on a face pieceof the mask for reception, together with the portion of hood coveringit, in an opening in a cover located on the outside of the hood. Thecover is provided with fitments for attachment of straps securing thecover to the helmet. Although the opening in which the projection isreceived may pass entirely through the cover, it will be appreciatedthat the opening may be in the form of a depression in the cover, thedepression having a constricted rim to grip the projection.

A problem experienced by the wearers of breathing masks is that changesof external air pressure lead to an imbalance in air pressure across theear drum, and to discomfort for the wearer. Some way of equalising theair pressure is therefore needed and typically this is achieved bypinching the nose, clenching the lips and exerting pressure as byexhaling, a technique known as valsalva. In the case of a pilot orworker who is required to wear goggles, pinching the nose may not bepracticable. The ability to pinch the nose effectively may also berestricted if thick gloves are being worn. A conventional breathing maskincludes an outlet port provided with an expiratory valve which opens asthe wearer exhales and through which the exhalate is vented. Accordingto a further aspect of the invention, the port may be provided with apart which may be depressed by finger or thumb pressure to close theport. The cover may be so shaped by, for example, being dished, so as toallow the wearer to locate it with ease, even when wearing thick gloves.With the port closed, the wearer may exhale vigorously, and it is foundthat the effect of this is to equalise the pressure in the ear canals.

The various aspects of the invention need not be employed together, buteither may be employed in a breathing mask without the other.

Other preferred features of all of the above aspects are set out in thedependent claims.

Specific embodiments will now be described, by way of example only, withreference to the accompanying drawings, in which:

FIG. 1 shows an impact-resistant and energy absorbing helmet in use;

FIG. 2 is a part section through the helmet shown in FIG. 1 with mask,visor and helmet-mounted equipment removed and showing a personalisedcap;

FIG. 3 shows a first hood adapted to be worn under the helmet shown inFIGS. 1 and 2;

FIG. 4 shows a second hood adapted to be worn under the helmet shown inFIGS. 1 and 2, illustrating the removable goggle and mask portion of thehood;

FIG. 5 shows a variant of the hood shown in FIG. 4;

FIG. 6 shows a mechanism by which a mask may be fitted in a mouth andnose portion of the hoods shown in FIGS. 4 and 5;

FIG. 7 shows a further hood adapted to be worn over a helmet;

FIG. 8 illustrates a helmet having a raisable visor, showing the visorin its raised position in dotted lines;

FIG. 9 shows the hood of FIG. 7 with the seal released and the visor ofthe helmet raised;

FIG. 10 a shows a further example in which the hood is worn between thehelmet and a custom-fitted inner cap;

FIG. 10 b shows further detail of a manifold adapted to be used with anenvironmental protection hood;

FIG. 10 c shows schematically details of fluid flow through a supply gasassembly for the manifold;

FIG. 10 d shows schematically a view of an exterior of a manifold;

FIG. 10 e shows schematically a view of an interior of the manifold ofFIG. 10 d;

FIG. 10 f shows schematically view of the connection between themanifold of FIGS. 10 d and e and an environmental protection hood;

FIG. 10 g shows an illustration of an environmental protection hood;

FIG. 11 illustrates a hood having a sleeve for hoses for providing airto a respirator mask and demisting air;

FIG. 12 is a schematic representation of a connection assembly at thedistal end of the sleeve for connecting hoses running through the sleeveto an air supply of an aircraft;

FIG. 13 is a part section through a first hose;

FIG. 14 is shows the structural helices of a second hose;

FIG. 15 show a sleeve forming the enclosure of a hose having an externalseam (FIG. 15A) and an internal seam (FIG. 15B);

FIG. 16 shows a mask suitable for use with the hoods and hoses shown inthe previous Figures;

FIG. 17 is a simplified schematic representation of a valve forming partof the mask shown in FIG. 16;

FIG. 18 shows a first embodiment of a fitting for attaching a mask to ahelmet or an under-helmet hood;

FIG. 19 shows a second embodiment of a fitting;

FIG. 20A illustrates the use of an air supply system having a secondaryair source above water level; and

FIG. 20B shows a buoyant secondary air source;

FIG. 21 diagrammatically shows a mask embodying the an aspect of theinvention;

FIG. 22 is an axial section through the fixing arrangement for the mask;

FIG. 23 diagrammatically shows a mask embodying a further aspect;

FIG. 24 a illustrates one type of mask in use; and

FIG. 24 b illustrates a further type of mask in use.

A first example of a system allowing a wearer of a helmet also to wearan environmental protection hood will first be described, in which thehood is to be worn under the helmet. A second example in which the hoodis worn over the helmet will then be described, followed by a thirdexample in which the hood is disposed between a custom-fitted innerliner and the outer shell of the helmet. Finally, further features whichmay be provided in connection with one or more of the examples will bedescribed.

FIG. 1 shows an impact-resistant and energy-absorbing helmet 2. Arespiratory mask 4 is provided to allow the user to breathe inconditions where this would otherwise be difficult or impossible, and avisor 6 depending from a helmet-mounted display unit or boss 7 isprovided to shield the wearer's eyes.

FIG. 2 is a schematic section through the helmet 2 with the mask 4, boss7 and visor 6 removed. The helmet comprises an outer shell 8 covering apersonalised cap 10 comprising a crown portion 12 (to cover the crown ofthe head of a wearer of the helmet) and a brow portion 14 (to cover thebrow). The crown and brow portions 12, 14 of the cap 10 are contiguouswith one another. The outer surfaces of the cap 10 are profiled toconform to the profile of the inner surface of the outer shell 8, suchthat relative movement of the cap 10 and the outer shell 8, when in use,is minimised.

The crown and brow portions 12, 14 of the cap 10 are formed inaccordance with data relating to the size and shape of the head of anintended user of the helmet obtained by gauging the profile of thewearer's head, for example by a measurement device operating by directmeasurement or by a non-contact method such as optical scanning, withoutan environmental protection hood so that when the wearer for whom thehelmet 2 was constructed wears the helmet without such a hood, it fitsclosely to his head, and the possibility of movement of the helmetrelative to the head is minimized.

In addition, an alternative brow portion 14′ (shown in dotted lines) ofthe cap 10 is provided. The outer surface of this alternative browportion is also profiled to conform to the profile of the inner surfaceof the outer shell 8. However, the inner surface of the alternative browportion 14′ is formed in accordance with data relating to the size andshape of the head of the intended user of the helmet while wearing anenvironmental protection hood so that when the wearer wears the helmetwith such a hood, the helmet fits closely to his head and, again, thepossibility of movement of the helmet relative to the head is minimized.In some embodiments it may be necessary also to change the crown portionto accommodate the environmental protection hood; then the alternativecrown portion 12′ (again shown dotted) is formed based on data definingthe size and shape of the user's head when wearing the hood. In thepreferred embodiment, the alternative brow portion 14′ is shaped toaccommodate a frame of the environmental protection hood (described inmore detail below).

At the interface between the crown and brow portions 12, 14 of the cap10, the portions engage with one another or interlock to inhibitrelative movement of the portions during use of the helmet. However, theportions may be removed from the outer shell 8 independently of oneanother; in particular, the brow portions 14, 14′ of the cap may beinterchanged without disturbing the crown portion.

Both portions of the cap 10 are formed of an energy or impact absorbingmaterial (for example, expanded polystyrene) in order to protect thewearer from injury in the event of an impact. Furthermore, the crownportion 12 of the cap is thicker than the brow portion 14, 14′ and, in aparticular embodiment, the portions are formed of different energy orimpact absorbing materials having different impact properties. The outershell 8 of the helmet also comprises crown and brow portions 16, 18respectively, which correspond approximately to the crown and browportions of the cap 10. The outer radius of the shell brow portion 18 isless than that of the shell crown portion to permit the attachment overthe brow portion of a helmet mounted display equipment. In conjunctionwith a thinner brow portion 14, 14′ of the cap 10, this allows thedisplay equipment to be mounted close to the eyes of the wearer of thehelmet.

In the preferred embodiment, the measurement device by means of whichdata relating to the size and head of the intended wearer of the helmetis a non-contact device (for example which scans the head of the wearerof the helmet optically). In order to ensure accurate fitting of thehelmet 2 and control over the attitude at which it sits upon the head ofthe wearer, the positions of the eyes of the wearer relative to oneanother and to the measured portion of his head are determined.

An environmental protection hood for use in conjunction with a helmethaving the above-described personalised cap will now be described.

FIG. 3 shows an environmental protection hood 40 to be worn under ahelmet. The hood is formed of a flexible material and is adapted to beclosing-fitting to the head of a wearer.

An aperture 42 in the flexible material is provided in a region of thehood intended to be situated in front of the eyes of the user when thehood is in use. The material of the hood at the periphery of theaperture is attached to a rigid frame 44, by means of which the shape ofthe aperture is maintained. The aperture is sealed by a removable clearwindow 46 through which a wearer of the hood may see.

Upper and lower clips 48, 50 are provided on the frame adjacent the browand the cheeks respectively of a wearer of the hood for engaging withclips in a helmet such that the frame and the window are positivelylocated relative to the helmet. In a preferred embodiment, the lowerclips 50 are adapted to engage with mask receivers in a helmet underwhich the hood is worn (described in further detail below with referenceto FIG. 6).

The hood further comprises a mask region 52, intended to be situatedadjacent a respiratory mask worn by the wearer of the hood, such thatthe mask is enclosed with the head of the wearer. At sides of the maskregion, that is to say in locations on the inner surface of the hood,adjacent the cheeks or the ears of a wearer of the hood, there areprovided receivers for receiving bayonets for locating the mask adjacentthe mouth of the wearer. While the receivers may be attached to theframe, in a preferred embodiment the receivers are not attached to theframe and the flexibility of the material between the receivers and thewindow allows the receivers to move relative to the window.

In a further embodiment, shown in FIG. 4, the mask region of the hood isremovable. In this embodiment, the frame 44 (the main frame)additionally defines an aperture 54 in the region of the mouth and noseof the wearer. The mask region of the hood comprises a further frame 56(the mask frame) having a shape corresponding to that of the main framesuch that the mask frame seals against the main frame. Clips 57 areprovided on the mask frame 56 which engage with clips 47 on the mainframe 44 to positively locate and seal the mask frame against the mainframe. In this embodiment, the lower clips 50 are provided on the maskframe 56.

In a variant of this embodiment (shown in FIG. 5), the aperture 54 inthe region of the mouth and nose of the wearer is not formed by the mainframe 44 but by a secondary frame 45.

Turning to FIG. 6, a mechanism for locating the mask within the hoodshown in FIG. 5 will be described. The mask region 52 of the hoodcomprises bayonets 50 for engaging with a helmet and a mask. Thebayonets 50 extend through the mask region of the hood, which is sealedaround them, to provide clips on the inside and the outside of the hood.On the outer surface of the mask 52, the bayonets 50 comprise clips 50′which are adapted to engage with the receivers in a helmet to which thebayonets 5 of the mask 4 are ordinarily attached when an under-helmethood is not worn. The bayonets 5 of the mask 4 (which may be the samemask which is used when a hood is not necessary and which may be customfit to a wearer) are removed, and the mask instead engages with theinterior clips 50″ of the hood bayonets 50. The air hose 104 attached tothe mask 4 is inserted into the sleeve 102 as described above.

As indicated above, in an alternative embodiment, the interior clips 50″and the exterior clips 50′ are not rigidly located relative to oneanother, in order to allow relative movement of the mask and the helmet.

The second example will now be described.

As indicated above, in this example, the hood is worn over a helmet forexample as shown in FIG. 1.

FIG. 7 shows a hood 80 being worn over a helmet (such as that shownschematically in FIG. 8). The hood is formed largely of a flexiblematerial which allows the hood conform to the shape of the helmet overwhich it is worn. A transparent window or visor 82 is provided in an eyeregion of the hood, through which the wearer of the hood may see. Areleasable seal 84 is provided along or adjacent the lower edge of thevisor 82. By releasing this seal, an opening may be made in the hood.

Turning to FIG. 8 an example of a helmet with which the hood may be worncomprises a head portion 92 and a helmet-mounted display unit (HDU)mounted on the head portion at pivots 96 so that the HDU may be raisedfrom a first position to a second position (shown in dotted lines). Atransparent visor 98 depends from the HDU 94.

When the hood 80 is worn with such a helmet 90, the hood visor 82 andthe helmet visor 98 are both situated in front of the eyes of thewearer. Adjacent the periphery of the hood visor 82 are provided clipswhich engage with the boss 94 to locate the visors 82, 98 in relation toone another. Thus, when the seal 84 is released, both the hood visor 82and the helmet visor 98 may be raised together, as shown in FIG. 9.

The third example will now be described with reference to FIG. 10, whichillustrates features of the example schematically.

As indicated above, in this example, the hood 400 (shown in dottedlines) is worn between a custom-fitted inner cap 402 and the shell 404of a helmet. The custom-fitted inner cap 402 extends across the top ofthe head of a wearer from a position roughly adjacent the brow to aposition above or roughly adjacent the external occipital protuberance.An impact attenuating liner 406 extending roughly from a positionroughly adjacent the crown of the head of the wearer to a position aboveor roughly adjacent the external occipital protuberance of the wearer isfixed inside the shell 404 of the helmet such that a portion of the hood400 adjacent the top and back of the head of the wearer is disposedbetween the cap 402 and the liner 406. In order to be able to locate thehelmet accurately and repeatable on the head of the wearer, thecustom-fitted cap 402 is shaped on its inner surface to fit closely thehead of the wearer, and on its outer surface to fit inside the shell 404and the liner 406 of the helmet with a hood 400 disposes therebetween.

A rigid frame 408 (having features in common with the rigid frame 44shown in FIG. 3) is provided around an aperture in the hood 400, inwhich is removably located a window 410. The frame 408 comprises on itsinner side (with reference to the helmet) a generally upward-opening,U′-shaped channel 409 which receives the forward edge of the cap 402,rigidly locating relative to one another the cap 402, the window 410 andthe shell 404 of the helmet.

A portion 401 of the hood 400 adjacent the mouth and nose of the weareris shaped to allow a mask (not shown) to be worn under the hood (asdescribed above). An oxygen mask manifold 412 is provided in an apertureadjacent this portion 401 of the hood 400. The manifold 412, shown inmore detail in FIG. 10 b, forms the sole point of entry for servicesinto the interior of the hood. On its external side, it includesfittings to receive an air hose in order to supply air to the mask and,via a hose 420, to a plurality of jets 422 formed in the frame 408adjacent the channel 409, the jets being arranged to direct air onto theinner surface of the window 410 to reduce or eliminate misting. Themanifold also comprises a connection for a drinking tube 414 forproviding a liquid to the wearer. Communications leads 416 extend from amicrophone (not shown) located in the mask and earphones 418 worn by thewearer down through the manifold 412.

The manifold may be covered by the material of the hood, and may bewelded into the hood. The presence of the manifold minimises the numbersof penetrations of the hood in order to convey services to the wearer.

A helmet mounted display 424 for providing the wearer with informationis provided on the forward side of the helmet.

The air flow through a supply conduit assembly 403 leading to themanifold 412 is shown in further detail in FIG. 10 c. The assemblycomprises a breathing supply tube 405, which supplies almost pure oxygenfor a wearer to breathe, and an air hose 407 which supplies air to thedemisting jets 422 described above. The oxygen mix supplied to thewearer is conditioned. The air supplied to the demister is notconditioned, but is filtered, as described below.

The breathing supply tube 405 is integrated with the air hose 407.Preferably, as shown in FIG. 10 c, the breathing supply tube is disposedwithin (preferably concentrically within) the hose 407. This arrangementmeans that only a single hose connection to the manifold 412 isnecessary. The tube 405 and hose 407 are both made from a lightweightmaterial.

The air hose 407 comprises an impeller 409 powered by a brushless motor411. The brushless motor is battery powered and the batteries disposedin a battery compartment 413. In normal circumstances the fluids in thebreathing supply tube and the air hose do not mix. Cockpit air is drawnby the impeller 409 through a filter 415 and a non-return valve 417 tothe manifold 412.

However, when the wearer undergoes exertion the oxygen supplied by thebreathing tube 405 may become insufficient. Internally the air hose 407and the breathing supply tube 405 are connected by a normally closedone-way top-up valve 417 and as the wearer breathes more heavily thepressure in the tube falls. At a given pressure, the top-up valve 419opens, to allow air from the air hose 407 to enter the breathing supplytube 405, and supplement the oxygen supply to the wearer. The non-returnvalve 417 prevents fluid flowing back from the hood under thesecircumstances.

FIG. 10 d-f show the manifold in more detail. The manifold 412 comprisesa variety of spigots: a oxygen supply spigot 451, a connector for adrinking straw arrangement 453, a dump-valve 455, a communications lead457, and an exhaust valve 459. The exhaust valve has a cover 461 whichthe pilot may close easily with a gloved hand to ease pressure in theears as described for part 609 of FIG. 23 hereinafter. In thisembodiment of the manifold an alternative demisting system is usedwhereby a small amount of the oxygen supply is used to demist the systemvia a separate bleed from the oxygen spigot. Custom rubber hoses (notshown) connect the various spigots with the masks. A different set ofrubber hoses may be used for interconnections with the various masks.The communications lead connects the mask microphone and headset to theexternal world. The connection between the environmental protection hoodand the manifold is shown in FIG. 10 f. A snout for 463 of theenvironmental protection hood is secured over a lip 465 of the manifoldusing a cable tie 467.

The hood (as described in any of the preceding examples) may be formedof a breathable (permeable one-way) fabric to increase wearer comfort.It may also be impregnated with a catalyst to promoteself-decontamination when the hood has been worn in harmfulenvironments. In order to increase wearer comfort still further, thehood may be formed of a translucent material to reduce or eliminate aclaustrophobic reaction by a wearer.

FIG. 10 g shows an arrangement which increases wearer comfort stillfurther. A goggle arrangement 421 is surrounded by a transparent (ortranslucent) plastics material 423. This increases the wearer'speripheral vision. It also makes manufacture of a hood 425 easier, asthe goggles 421 may be glued or welded to the plastic surround 423,which in turn may be glued or welded to the otherwise-opaque hood 425.

The detail shown in FIG. 10 d gives an example of materials which may beused for the hood 425. The hood 425 comprises a three layer structure,an inner layer 427 which comprises an absorptive comfort liner, a middlelayer 429 which comprises a Lycra® fit/control layer, and an outer layer431 which comprises a barrier fabric.

Turning to FIG. 11, a further system for providing air to a respiratorymask worn together with the hood will now be described. This system isapplicable equally to the under-helmet hood 40 and the over-helmet hood80 described above.

The hood 100 comprises a sleeve 102 formed of the same flexible materialas the main body of the hood. A hose 104 for feeding air to arespiratory mask 105 worn by the wearer of the hood is inserted into thesleeve and the proximal end of the hose 104 is connected to the mask ina known manner.

Also running through the sleeve is a further hose 106 for supplyingdemisting air to the window 101 of the hood 100.

At the distal end of the sleeve is provided a connection assembly 110(see FIG. 12). The connection assembly comprises a socket 112 on theinside of the sleeve in flow communication with a plug 114 on theoutside of the sleeve. The socket 112 is adapted to receive and retainthe hose 104 for supplying air to the mask 105 (which may, for example,be as currently used to supply air to respiratory masks in aircraft) andthe further hose 106 for supplying demisting air. The sleeve is sealedaround the connection assembly 110, but air may pass into the hoses fromthe air supply of an aircraft via the connection assembly. In this way,air may be supplied to the mask 105 by means of a hose which is enclosedin the hood. In the case of a hood intended to be worn over a helmet,cables for power, data and communications also reach the helmet via asleeve (for example, the sleeve 102 shown in FIGS. 11 and 12.

A hose suitable for use with the above-described systems will now bedescribed with reference to FIGS. 13 and 14.

FIG. 13 shows a first hose 120 comprising an enclosure means in the formof a silicone rubber wall 122 shown in cross-section, and structuralmeans, for maintaining the structure of the hose, in the form of twocoaxial helices, one 124 running inside the other 126. The inner helix124 is right-handed while the outer helix 126 is left-handed, and theirradii are similar such that there is contact between the helices wherethey cross one another. In some embodiments, the helices may be bondedto one another. Furthermore, the helices may float freely within theouter wall 122, they may be bonded to it along their length (forexample, using a thin film adhesive), or they may be constrainedrelative to the wall at either or both ends. In a particular example,the structural means is formed as a tape which is wound around thehelices.

The helices are formed of a thermoplastics material such as nylon,polyethylene or polypropylene by extrusion.

FIG. 14 shows an alternative structural means 130 comprising aleft-handed outer helix 132 around three right-handed inner helices 134,136, 138. The inner helices 134, 136, 138 have smaller cross-sections(i.e. the cross-section of the material forming the helix, rather thanof the helix itself) than the outer helix 132. The helices are again ofextruded thermoplastics material.

Further embodiments are possible having one or more helix in eachdirection, the helices being of various cross-sections and pitch and invarious arrangements. However, the cross-sections, pitch and arrangementof the helices are chosen so as to minimise the torque around the axisof the hose produced when the hose is compressed or stretched. Forexample, in the arrangement shown in FIG. 11, the helices are ofidentical cross-section and identical pitch.

In further embodiments intended for use in the presence of contaminantsto which silicone is transparent, the enclosure means (122′ and 122″ inFIG. 15) of the hose may be formed from an elongate sheet of a material,e.g. an impermeable fabric, the long edges of which are sealed together,e.g. stitched and bonded or welded, to produce a sleeve 122′, 122″ whichmay be used with the seam 123 external (see FIG. 15A) or inverted suchthat the seam 123 is internal (FIG. 15B). The sleeve may then be fitted(or indeed it may be formed) around the outside of the structural means(e.g. helices as described above) or it may be inserted within thestructural means, at least portions of which are then bonded to thesleeve such that they maintain the lumen of the sleeve.

In yet further embodiments (not shown), the enclosure means may beformed of an elongate material (e.g. an impermeable fabric) which iswound around the structural means in an overlapping helicalconfiguration and bonded in the overlapping regions to provide animpermeable enclosure.

A mask will now be described which may be used in conjunction with theabove-described systems.

With reference to FIG. 16, the mask comprises a rigid unit 240 whichhouses all of the common elements of the respirator, such as aninspiratory valve unit, an expiratory valve and a communicationsmicrophone. The unit 240 is connected to a supply hose 242 for thesupply of breathing gas to a wearer, such as an airman. The unit 240 isformed by injection moulding of a thermoplastics material such as nylon,and is moulded to have interior surfaces of the mask which serve asvalve seats for the inspiratory valve and expiratory valves, andcavities or depressions which serve as pressure chambers for the valves.

FIG. 17 is a simplified schematic representation showing a valve 210 inthe wall of the unit 240. The valve comprises a cavity 262 defined inthe wall of the unit 240, which serves as a chamber of the valve. Thechamber is closed by a cover 264 which screws into the opening in thechamber 262. The cover comprises openings 266 to allow exhalate into thechamber, and a side wall of the chamber comprises a further opening 268to allow the exhalate to leave the chamber.

Opposing depressions in the cover 270 and the wall of the unit 240 serveto locate a shaft 272 upon which is mounted a valve disc 274. The disc274 is slidable along the shaft 272 and is urged by a spring 276 towardsthe cover 264 where it seals the openings 266, preventing air fromoutside the mask entering the mask via the chamber 262.

While the valve shown is simplified in order to provide a clear example,the principle is equally applicable to inspiratory and expiratoryvalves, including valves through which air is to be breathed underpressure.

The unit 240 is a common element of the breathing mask, in that it issupplied in common to many airmen regardless of facial size and/orshape. The unit 240 is connected to a pre-formed unit 244 having aflexible body moulded from, for example, rubber material, for sealing toan airman's face. The inner surface of the body may be moulded withfeatures 247 which prevent the reflex edge of the sealing surface of theunit from becoming inverted under pressure.

The pre-formed unit 244 is a sized component, which may also be shapedto suit differing racial characteristics, selected from a range of suchunits 244 according to the size and/or shape of the wearer's face. Thepre-formed unit 244 could even be bespoke to a particular user, beingmanufactured to suit the contours of an individual's face.

The units 240, 244 are assembled by threading the supply hose 242 thoughaperture 248 in the unit 244 and drawing the unit 244 around the unit240 so that lip 250 of the unit 244 engages the raised edge 252 of theunit 240. A rigid clamping unit 254, which may be formed from mouldedplastics material, is, like the unit 244, a sized component and selectedfrom a range of similar units in accordance with the particular unit 244chosen for the airman. The clamping unit 254 is assembled to the units240, 244 by similarly threading the supply hose 242 through the aperture256 and drawing the clamping unit 254 around unit 240 to engage the unit244. The clamping unit 254 may be secured by a snap-fit or by anyconventional fastening.

Finally, fittings to allow a mask to be located within a helmet or anunder-helmet hood are described with reference to FIGS. 18 and 19.

FIG. 18 shows a first embodiment of a fitting which comprises anelongate bayonet assembly 302 adapted to engage with receivers in ahelmet, and a steelwork portion 304. The steelwork portion 304 comprisestwo rotatably mounted discs 306, each having a slot 307 through whichmay be passed webbing 308 for attaching the fitting to the mask. FIG.18A shows the fitting with the discs oriented such that webbing passingthrough the discs extends in a direction parallel to the axis of thebayonet assembly. In FIG. 18B, the same fitting is shown with the discsrotated slightly so that the webbing extends away from the axis of thebayonet assembly 302.

FIG. 17 shows a second embodiment of a fitting 300′, similar to thatshown in FIG. 18 with the exception that, instead of discs, thesteelwork portion 304 comprises arcuate inserts 310 slidably mounted inarcuate slots 312 having the same radius of curvature as the inserts310, such that they may slide between the ends of the slots 312. Each ofthe inserts 310 contains a further slot 314 through which may be passedwebbing 308 for attaching the fitting to the mask. FIG. 19A again showsthe webbing extending in a direction parallel to the axis of the bayonetassembly 302. In FIG. 19B, the same fitting 300′ is shown with theinserts rotated slightly so that the webbing extends away from the axisof the bayonet assembly 302.

Finally, embodiments of a device to enable the wearer (e.g. aircrew) ofan oxygen mask of the type with which the above-described items may beused (e.g. close-fitting such that the wearer may breathe only via themask) to breathe in the event that they find themselves in water 498,for example, after having ejected over the ocean (see FIG. 20A).

Air is provided to the mask via a hose 500 a distal end of which isattachable to an aircraft air supply via a plug 502 and socket (notshown) arrangement. The hose 500 feeds a first inlet of a block 504provided in the hose adjacent the chest of the user of the mask. When inuse in an aircraft, air is provided to the hose by the aircraft airsupply under pressure, and a pressure switch in the block 504 maintains(by action of the air pressure) flow communication between the plug 502and the mask when air pressure at the first inlet of the block isgreater than a threshold pressure. However, when the air pressure at thefirst inlet falls below the threshold pressure, the pressure switch isreleased and is biased to allow flow communication between the mask anda further hose 506 connected to a second inlet of the block 504. At itsdistal end, the further hose is connected to a snorkel unit 508 which isfixed to the shoulder region of the wearer's buoyancy device 510 byreleasable means, such as a thread having a low tensile strength.

The snorkel unit additionally comprises a flotation bladder 512 (seeFIG. 20B) which is inflated automatically upon or shortly after contactwith water by a CO₂ canister having a soluble spring trigger of a knowntype (for example as used in air line life vests) in which, upon contactwith water, a trigger of a soluble material dissolves releasing abayonet which is biased towards the canister. The bayonet punctures thecanister, releasing the pressurised CO₂ and inflating the bladder. Thebladder is arranged such that when inflating it causes the snorkel unitto be released (e.g. by snapping the thread holding the unit to the lifevest) and to float at the surface.

An inlet 514 of the snorkel unit 508 allows air to enter, while baffles516 prevent or inhibit the ingress of water, for example in rough seas.

A further mask will now be described which may be used in conjunctionwith the above-described systems.

Referring to FIG. 21, a pilot is provided with an environmentalprotection hood 603 worn under a helmet 604. A breathing maskincorporates a face piece which is worn under the hood (and not visiblein FIG. 21) and a cover or exoskeleton 602 which is worn externally ofthe hood and is connected to the helmet by strapping, 605 and a bayonetfitting 605 a which is retained in a receiver 605 b attached to thehelmet 604, as for example in GB 2313399. A hose 606 supplies air to theface piece of the mask.

This arrangement enables different types of masks to be used with anenvironmental protection hood.

The face piece is secured to the cover by an arrangement incorporating astud 601 provided on the face piece and capable of inter-fitting with anopening 607 in the cover. The stud is of mushroom-like shape and has anenlarged head as shown in FIG. 22 so as to be a snap-fit in the opening,with the material of the hood trapped between the stud and the cover.The stud may be readily snapped into the opening and released from it,but reliably secures the two parts of the mask when interlocked with it.

Referring now to FIG. 23, a breathing mask is provided with anexpiratory valve having an outlet port 610 covered by a finger piece609. The construction of the valve may be as described in UK PatentApplication No. 0311338.8, but may alternatively be of any suitableknown type. It is arranged to close as the wearer inhales, and to openas the wearer breathes out. When in its normal position the cover 609does not interfere with this manner of operation but may be depressed toclose the port 610 when it would normally be open.

In order to ease discomfort in the ears, the wearer of the mask may usethe finger piece 609 to close the port and at the same time exhalestrongly, and then release the finger piece.

The finger piece may take the form of a cover for the outlet portretained by a central spigot 611 and arranged to close the port whendepressed. Alternatively the finger piece may be coupled to the valveand serve to over-ride and close it when it would normally be open. Thefinger piece may be so shaped as to be easily identifiable by touch, asby being dished.

FIGS. 24 a and 24 b illustrate different types of mask in use. Straps612 attach an outer component, or exoskeleton 614, to the helmet whenthe wearer puts the helmet on, as also shown in FIG. 21 and describedabove. The use of such an exoskeleton enables different types of mask tobe used interchangeably.

Statements in this specification of the “objects of the invention”relate to preferred embodiments of the invention, but not necessarily toall embodiments of the invention falling within the claims. Thedescription of the invention with reference to the drawings is by way ofexample only. Each feature disclosed in the description, and/or theclaims and drawings may be provided independently or in any appropriatecombination. In particular, a feature of a subsidiary claim may beincorporated into a claim upon which it is not dependent.

Each feature disclosed in this specification (which term includes theclaims) and/or shown in the drawings may be incorporated in theinvention independently of other disclosed and/or illustrated features.

Statements in this specification of the “objects of the invention”relate to preferred embodiments of the invention, but not necessarily toall embodiments of the invention falling within the claims. Thedescription of the invention with reference to the drawings is by way ofexample only.

The text of the abstract filed herewith is repeated here as part of thespecification.

A personalised cap 10 for use with a protective helmet is disclosed,having crown and brow portions 12, 14. The brow portion 14 is removableindependently of the crown portion 10, and an alternative brow portion14′ is provided for use when a environmental protection hood is to beworn under the helmet. An alternative crown portion 12′ also may beprovided.

A hood for use over a helmet and a hose for use to provide air to arespiratory mask, a mask and fittings for attaching a mask to a helmetare also disclosed. The environmental protection hood may comprise amanifold 412 having an element external to the hood, for receivingsupply of services needed within the hood, and an element internal tothe hood, for providing those services where required.

1-111. (canceled)
 112. An environmental protection hood comprising amanifold having an element external to the hood, for receiving supply ofa plurality of services needed within the hood, and an element internalto the hood, for providing those plurality of services where required.113. A hood according to claim 112, wherein the external element has aninlet for receiving a breathing supply and wherein the internal elementis adapted for feeding a breathing mask.
 114. A hood according to claim112, wherein the external element has an inlet for receiving a liquid.115. A hood according to claim 112 wherein the services includeelectrical wiring for communications.
 116. A hood according to claim112, wherein the internal element is adapted for feeding a demisting jetof air for demisting or inhibiting misting of a window of the hoodand/or for ventilating the hood.
 117. A hood according to claim 113,wherein the internal element is adapted for feeding a demisting jet ofair for demisting or inhibiting misting of a window of the hood and/orfor ventilating the hood and wherein the external element has an inletfor receiving air disposed within the inlet for receiving a breathingsupply or vice versa.
 118. A hood according to claim 113 in combinationwith a supply conduit assembly comprising a breathing gas conduit, anair conduit and a diverter for diverting air from the air conduit to thebreathing conduit if a supply of breathing gas is insufficient.
 119. Ahood according to claim 118 comprising a powered impeller for increasingair pressure in the air conduit.
 120. A hood according to claim 118,wherein the air conduit comprises a filter for removing contaminantsfrom the air passing therethrough.
 121. A hood according to claim 118,wherein the diverter comprises a normally-closed valve between thebreathing gas conduit and the air conduit.
 122. A hood according toclaim 118 comprising a non-return valve to prevent air flowing back fromthe hood when air is diverted to the breathing conduit.
 123. A hoodaccording to claim 112, wherein the manifold comprises a breathingoutlet port, a valve associated with the outlet port, the valve openingwhen a wearer of the hood exhales, and a mechanism operable by thewearer for closing the port when the wearer exhales.
 124. A hoodaccording to claim 123, wherein said mechanism comprises a cover for theport, the cover being capable of being depressed or otherwise movedmanually to close the port.
 125. A hood according to claim 123, whereinthe cover is so shaped as to be readily identifiable by touch.
 126. Ahood according to claim 112, in combination with a protective helmethaving an outer shell and an inner cap, the hood being disposed betweenthe shell and the cap.
 127. A hood according to claim 126, wherein thehood has a window aperture, and location formations adjacent theaperture for engaging with the cap and the helmet.
 128. A breathing maskfor use with an environmental hood, the mask including a component forlocation within the hood and a component for location externally of thehood, one of the components being provided or associated with aprojection capable of being pressed into the material of the hood, andthe other component having an opening for receiving and retaining theprojection and the portion of the hood to which it is applied.
 129. Abreathing mask as claimed in claim 128, wherein the projection has anenlarged head which is shaped to be retained in the opening.
 130. Abreathing mask as claimed in claim 129, wherein the opening is definedby resilient material so that the projection is a snap-fit therein. 131.A breathing mask having an outlet port, a valve associated with theoutlet port, the valve opening when a wearer of the mask exhales, andmeans operable by the wearer for closing the port when the wearerexhales.